I hate threads making me feel old, I'm still too young for that
At 16, I was playing a lot of guitar, giving up on upgrading my PC every 5 minutes, sitting round a fire in a random field chatting nonsense, going round to friends' houses and just...talking/finding things to do. It was never really an issue - though come to think of it, I've no idea how we spent all day at school together, all evening talking online and then still filled whole days together at the weekends. I guess having a mixed sex friendship group with lots of drama and suspicions helped keep it interesting

Worked on Saturdays to save up and let me go to Italy with my best friend for 2 weeks in the Summer, went for nighttime wanders in the countryside, took photos wherever I went, found a whole load of new music I'd never discovered, and started getting in to sound/lighting, which led me on to a whole new group of friends and experiences.
Also, we released a line of tshirts with a bunch of designs my slightly demented friend created and sold them in school - made a decent bit of money at the time, counted as a project and was good fun too.
Basically, there's loads to do, get involved in something which doesn't involve your friends and their...I can't bring myself to use that word, but y'know, the things that make those vile noises.